Longitudinal Comparison of PNES spell and ASM reduction in PNES Patients with and without Epilepsy Discharged from an Epilepsy Monitoring Unit

Abstract

Objective: To examine trends of Antiseizure Medication (ASM) reduction and discontinuation, as well as Psychogenic Non-Epileptic Seizure (PNES) spell reduction and resolution in patients with PNES, with and without comorbid epileptic seizures (ES).

Methods: A retrospective analysis was conducted on data from 145 patients with PNES, including 109 with PNES alone and 36 with PNES plus comorbid epilepsy. Patients were admitted to the Epilepsy Monitoring Unit (EMU) between May 2000 and April 2008, with follow-up clinical data collected until September 2015. Clinical records were thoroughly examined, encompassing the period preceding the PNES diagnosis until either loss to follow-up or September 2015. A subsequent chart review was conducted by two neurologists, covering the period following the diagnosis of PNES until either loss to follow-up or September 2015, which ever came first.

Results: Patients with PNES alone had higher rates of ASM reduction for all variables of ASM reduction measured compared to those with comorbid epilepsy (all at p < 001). Among patients with PNES alone, reductions in ASMs were observed after EMU discharge, but an uptick and plateau were seen in later follow-up years (100% of patients free of ASMs at years 2-3, 20% on at least one ASM by year 7). This pattern differs greatly in PNES + ES patients, in which the only time point at which any patient was able to discontinue all ASMs was at EMU discharge (4.5% of patients), with all patients taking at least one ASM for every other follow-up time point. Reductions in PNES spell frequency did not differ significantly between the two groups (for example PNES spells reduced at final FU 47.2% vs 42.9%, p = 0.65). In both groups, despite an initial drop in variables of PNES spell reduction and resolution in the early years post discharge, there is an eventual rebound and plateau (for example in PNES only patients, 33.9% of patients having no resolution in 1st year FU, which rises to 78% at years 4-5, and plateus around 52.8% at more than 7 years follow-up.) SIGNIFICANCE: This study contributes to the growing body of research focused on improving the current approach to management and prognostic outlook of PNES. Although PNES only patients had higher rates of ASM reduction, the uptick and plateau observed in later years highlights the challenges in managing PNES. Similarly, the continued persistence and rebound of PNES spells underline the continued poor prognostic outcomes associated with this condition.

Keywords: Epilepsy; Functional neurological disorder; Psychogenic non-epileptic seizure; course of illness; outcomes.